Dynamic EMI (electromagnetic interference) management

ABSTRACT

In one embodiment, a method is provided. The method may include determining if electromagnetic interference (EMI) is emitted by a device in one or more regions of an electromagnetic spectrum occupied by other users, and if it is determined that EMI is emitted by the device in one or more regions of the electromagnetic spectrum occupied by other users, reducing the EMI in the one or more regions, and increasing the EMI in one or more other regions unoccupied by the other users.

FIELD

Embodiments of this invention relate to the field of dynamicelectromagnetic interference (hereinafter “EMI”) management.

BACKGROUND

In the course of operation of a device, the device may emit EMI(hereinafter “electromagnetic interference”) into an electromagneticspectrum, such as a radio frequency (hereinafter “RF”) spectrum. The RFspectrum is regulated by the FCC (Federal Communications Commission),and rules regarding the use thereof is proscribed under Part 15 of theFCC Rules (Code of Federal Regulations, Title 17, hereinafter referredto as “FCC Rules”). Under the FCC Rules, for example, a device thatunintentionally or incidentally emits EMI must maintain EMI levels belowa fixed, predetermined level.

In non-communications devices, the emitted EMI may nevertheless exceedthe defined (by the FCC, for example) EMI levels for some frequencies.In communications devices, a conflict may exist between increasing thetransmission capacity of the device on a given channel, and maintainingthe EMI at acceptable levels, such as those defined by the FCC. Thefollowing Shannon equation, which gives the transmission capacity of agiven channel, may illustrate a source of this conflict:

$C = {\int{{\log_{2}\left( {1 + \frac{s(f)}{N(f)}} \right)}{\mathbb{d}f}}}$

where C is the channel capacity in bits/second, s(f) is the receivedsignal PSD (power spectral density) in watts/Hz, and N(f) is the noisePSD in watts/Hz. The channel capacity may be improved by factors such asimproved coding schemes, techniques which help to reduce the effectivenoise level, such as crosstalk cancellation, and increasing the receivedsignal PSD. For a given channel with a given response, however, anincrease in s(f) may result in an increase in launch power, i.e., anincrease in the power of the signal injected into the channel by thedevice. Unfortunately, increasing the launch power may result inincreasing the EMI beyond acceptable levels.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example,and not by way of limitation, in the figures of the accompanyingdrawings and in which like reference numerals refer to similar elementsand in which:

FIG. 1 is a diagram illustrating a system embodiment.

FIG. 2 is a flowchart illustrating a method according to an embodiment.

FIG. 3 is a flowchart illustrating a method according to anotherembodiment.

FIG. 4 is a flowchart illustrating a method according to anotherembodiment.

DETAILED DESCRIPTION

Embodiments of the present invention include various operations, whichwill be described below. The operations associated with embodiments ofthe present invention may be performed by hardware components or may beembodied in machine-executable instructions, which when executed mayresult in a general-purpose or special-purpose processor or logiccircuits programmed with the instructions performing the operations.Alternatively, and/or additionally, some or all of the operations may beperformed by a combination of hardware and software.

Embodiments of the present invention may be provided, for example, as acomputer program product which may include one or more machine-readablemedia having stored thereon machine-executable instructions that, whenexecuted by one or more machines such as a computer, network ofcomputers, or other electronic devices, may result in the one or moremachines carrying out operations in accordance with embodiments of thepresent invention. A machine-readable medium may include, but is notlimited to, floppy diskettes, optical disks, CD-ROMs (Compact Disc-ReadOnly Memories), and magneto-optical disks, ROMs (Read Only Memories),RAMs (Random Access Memories), EPROMs (Erasable Programmable Read OnlyMemories), EEPROMs (Electromagnetic Erasable Programmable Read OnlyMemories), magnetic or optical cards, flash memory, or other type ofmedia/machine-readable medium suitable for storing suchmachine-executable instructions.

Moreover, embodiments of the present invention may also be downloaded asa computer program product, wherein the program may be transferred froma remote computer (e.g., a server) to a requesting computer (e.g., aclient) by way of one or more data signals embodied in and/or modulatedby a carrier wave or other propagation medium via a communication link(e.g., a modem and/or network connection). Accordingly, as used herein,a machine-readable medium may, but is not required to, comprise such acarrier wave.

Examples described below are for illustrative purposes only, and are inno way intended to limit embodiments of the invention. Thus, whereexamples may be described in detail, or where a list of examples may beprovided, it should be understood that the examples are not to beconstrued as exhaustive, and do not limit embodiments of the inventionto the examples described and/or illustrated.

The functionality of each component as described below may beimplemented in hardware as circuits. As used herein, a circuit thatcarries out certain functionality may comprise circuitry (which may be asingle circuit, or a plurality of circuits), and may be programmed withinstructions to perform the functionality. A circuit may comprise adigital circuit, an analog circuit, a state machine, programmablecircuitry, and/or an ASIC (application specific integrated circuit).

Introduction

FIG. 1 illustrates a system 100 in accordance with an embodiment of theinvention, and FIG. 2 illustrates a method in accordance with anembodiment of the invention. The method begins at block 200 andcontinues to block 202 where circuitry 104 may determine if a device 102emits EMI 106 in one or more regions 112 of an electromagnetic spectrum110 occupied by other users 116. At block 204, if circuitry 104determines that the device 102 emits EMI 106 in one or more regions 112of the electromagnetic spectrum 110 occupied by other users 116, thencircuitry 104 may reduce the EMI 106 in the one or more regions 112occupied by the other users 116, and increase the EMI 106 in one or moreother regions 114 unoccupied by the other users 116. The method ends atblock 206. If it is determined that the device 102 does not emit EMI 106in one or more regions 112 of the electromagnetic spectrum 110 occupiedby other users 116, then the method ends at block 206.

FIG. 3 illustrates a method in accordance with another embodiment of theinvention. The method begins at block 300 and continues to block 302where circuitry 104 may determine if a device 102 emits EMI 106 in thepresence of other users 116 in an electromagnetic spectrum 110. If it isdetermined that the device 102 emits EMI 106 in the presence of otherusers 116 in the electromagnetic spectrum 110, then at block 304circuitry 104 may determine if the device's 102 current location 118 isthe same as its previous location 120. At block 308, if the device's 102current location 118 is the same as its previous location 120, thencircuitry 104 may reduce the EMI 106 of the device 102 in one or moreregions 112 of an electromagnetic spectrum 110 occupied by the otherusers 116, and increase the EMI 106 in one or more other regions 114 inthe electromagnetic spectrum 110 unoccupied by the other users 116. Themethod ends at block 310.

If at block 302 it is determined that the device 102 does not emit EMI106 in the presence of other users 116 in the electromagnetic spectrum110, then the method ends at block 310. If at block 304 it is determinedthat the device's 102 current location 118 is not the same as itsprevious location 120, then at block 306, circuitry 104 may determineone or more regions 112 of the electromagnetic spectrum 110 occupied bythe other users 116. The method continues to block 308, as describedabove, and ends at block 310.

Circuitry 104 may determine if a device's 102 current location 118 isthe same as its previous location 120 by using a memory 108. Memory 108may store a previous location 120 of the device. In one embodiment, forexample, a device 102 may store its location in memory 108. To determineif the device's 102 current location 118 has changed from its previouslocation 120, circuitry 104 may compare the location 120 stored in thememory 108 to the device's 102 currently determined location 118. Whilememory 108 is shown as located outside of device 102, memory 108 is notrestricted to this location, and may reside anywhere. For example,memory 108 may reside on the device 102 itself, and circuitry 104 mayaccess memory 108 on device 102.

Another embodiment of a method is illustrated in FIG. 4, which begins atblock 400 and continues to block 402 where circuitry 104 may determineif a device 102 emits EMI 106 in unacceptable levels 124 in or moreregions 126 of an electromagnetic spectrum 110. At block 404, ifcircuitry 104 determines that the device 102 emits EMI 106 inunacceptable levels 124 in one or more regions 126 of theelectromagnetic spectrum 110, then circuitry 104 may reduce EMI 106 inthe one or more regions 126, and increase EMI 106 in one or more otherregions 128 of the electromagnetic spectrum 110 where the increased EMI106 levels are acceptable 122. The method ends at block 406. If it isdetermined that the device 102 does not emit EMI 106 in unacceptablelevels 124 (i.e., levels are acceptable 122) in one or more regions 126of the electromagnetic spectrum 110, then the method ends at block 406.

In FIG. 1, electromagnetic spectrum 110 may comprise a portion of a fullelectromagnetic spectrum. Also, regions 112, 114, 126, 128 may bearbitrary regions within a full electromagnetic spectrum, such asregions in electromagnetic spectrum 110. Regions 112, 114, 126, 128should not be construed as specific ranges, or specific portions, andshould not be construed as being limited to portions of a fullelectromagnetic spectrum. Rather, regions 112, 114, 126, 128 areillustrative, and are intended to illustrate occupied regions 112relative to unoccupied regions 114, and/or regions where particular EMIemissions are unacceptable 126 as opposed to acceptable 128.

As used herein, “EMI” 106 may refer to interference that may potentiallydisrupt, degrade or otherwise interfere with electromagnetic radiationemitted within one or more regions of an electromagnetic spectrum 110.Other EMI 106 may include microwave interference, and radio frequency.An electromagnetic spectrum 110 may include a radio frequency spectrum,for example.

In one embodiment, circuitry 104 may additionally determine whether adevice 102 unintentionally emits EMI 106. As used herein, a device 102may unintentionally emit EMI 106 if its emission of EMI 106 isincidental to its operation and/or is not deliberate to its operation. Adevice 102 my incidentally emit EMI 106 if the device 102 is likely toemit EMI 106, but its emission may be unpredictable in the course ofoperation, or may be a minor accompaniment to its operation. In oneembodiment, a device 102 may incidentally emit EMI 106 if it “generatesradio frequency energy during the course of its operation although thedevice is not intentionally designed to generate or emit radio frequencyenergy.” FCC Rules, Rule 15, Section 15.3(n).

A device 102 that emits EMI where the emission is not deliberate to itsoperation may be a device that emits EMI 106 as an unintended result ofits operation. In one embodiment, a device 102 emits EMI 106 as anunintended result of its operation if it “generates radio frequencyenergy for use within the device, or . . . sends radio frequency signalsby conduction to associated equipment via connecting wiring, but whichis not intended to emit RF energy by radiation or induction.” FCC Rules,Rule 15, Section 15.3(z).

A device 102 that may unintentionally emit EMI 106 may comprise anon-communications device or a communications device. A PC (personalcomputer) is an example of a non-communications device, and a DSL(Digital Subscriber Line) transceiver is an example of a communicationsdevice. These are simply examples for illustrative purposes only, andare not intended to limit embodiments of the invention.

A “user” may be a transmitter (and/or receiver) that may communicateusing a specific transmit and receive frequency combination. Inembodiments of the invention, a user may comprise a device 102 thatintentionally, unintentionally, and/or incidentally emits EMI 106 intoone or more regions 112, 114, 124, 126 of an electromagnetic spectrum110. A user may be an active user and/or a licensed user. A licenseduser may be a user that has a frequency (specific frequency or a range)assigned to it. Frequencies may be assigned to users by the FCC, forexample, and may be coordinated with other users of the same radiofrequency spectrum in the same geographical area. An active user may bea user that may communicate concurrently as a device checking for thepresence of other users. In embodiments of the invention, a user may bea licensed user (active or inactive), and/or an active user (licensed orunlicensed).

As used herein, a “region” may include a specific frequency, or a rangeof frequencies. Thus, “one or more regions” may include any combinationof one or more specific frequencies and/or one or more range offrequencies. In a radio frequency spectrum, for example, a region maycomprise a specific radio frequency, such as 130.5 MHZ (MegaHertz).Alternatively, a region may comprise a range of radio frequencies, suchas 140.5 MHz to 150.5 MHz. One or more regions may include radiofrequencies 120.5 MHz and/or 130.5 MHz, and/or 140.5 MHz to 150.5 MHz,for example.

“Acceptable level” 122, as used herein, may refer to an amount ofemitted EMI 106 that may be permitted in accordance with a predeterminedstandard and/or at or below a predetermined threshold. An acceptablelevel 122 of EMI may be pre-defined, such as by the FCC, or dynamic.Conversely, an “unacceptable level” 124, as used herein, may refer anamount of emitted EMI 106 that may not be permitted in accordance with apredetermined standard and/or above a predetermined threshold. Anacceptable level 122 of EMI 106 may differ from one region to anotherregion in an electromagnetic spectrum 110. Also, an acceptable level 122of EMI 306 may differ for different devices, and/or be dependent onother factors.

In one embodiment, EMI 106 may be altered if there are other users 116present, whether EMI levels may be acceptable 122 or unacceptable 124.In another embodiment, EMI 106 may be altered if EMI levels areunacceptable 124 whether other users 116 may be present. In still otherembodiments, EMI 106 may be altered if EMI levels are unacceptable 124,and there are other users 116 present.

Determining if a Device Emits EMI into a Region Occupied by Other Users.

In one embodiment, determining if a device 102 emits EMI 106 into one ormore regions 112 occupied by other users 116 may comprise determining apresence of other users 116 at the device's location 118, and if thereare other users 116 present at that location 118, determining one ormore regions 112 of the electromagnetic spectrum 110 occupied by theother users 116 at that location 118.

In one embodiment, the presence of other users 116 at the device'slocation 118 may comprise accessing a database 130 of users at thedevice's location 118. A device's location 118 may be determined byobtaining location information from a GPS (Global Positioning System),for example. Other means, such as triangulation, may be used. These aremerely examples, and other methods existing now and not mentionedherein, or which may exist in the future may be used. The determineddevice location 118 may be correlated with a database 130 of users atthe location 118. One or more users in database 130 may mean that otherusers are present. For example, if the device 102 knows it is located ina certain metropolitan area (i.e., location), it can determine whichregions of the radio and TV broadcast spectrum are occupied andunoccupied by local users.

In another embodiment, the presence of other users 116 at the device'slocation 118 may be determined by listening to the electromagneticspectrum 110. By the principle of reciprocity, devices 102 that may beefficient generators of EMI at a given frequency may also be capable ofefficiently listening at that frequency. An example of this may includeDMT (Discrete Multitone) DSL transceivers, which may use adaptivewater-filling algorithms for performing bit-loading of the frequencybins. In the presence of licensed radio users, for example, such modemsmay use convert tonal techniques to detect the coupling of radio signalsto the twisted-pair line.

Determining one or more regions 112 of the electromagnetic spectrum 110occupied by the other users 116 at a device's location 118 may comprise,for example, accessing a database 130 of users at the device's location.Database 130 may comprise a list of one or more users, as well as one ormore regions occupied by the one or more users.

In one embodiment, if circuitry 104 determines that the device's 102current location 118 is the same as the device's previous location 120,then circuitry 104 may reduce the EMI 106 in the one or more regions 112of the electromagnetic spectrum 110 occupied by the other users 116, andincrease the EMI 106 in the one or more other regions 114 of theelectromagnetic spectrum 110 unoccupied by the other users 116. If thecurrent location 118 is not the same as the device's previous location120, then circuitry 104 may first determine the one or more regions 112of the electromagnetic spectrum 110 occupied by the other users 116 at adevice's location 118.

Reducing EMI in Occupied Regions, and Increasing EMI in UnoccupiedRegions

EMI 106 emissions may be reduced in occupied regions 112, and increasedin unoccupied regions 114 in a number of ways. For example, DMT devicesmay modify their EMI 106 in the course of operation. Computing devicesmay change a characteristic (such as frequency or clock signal shape) oftheir clock signal(s). These examples are illustrative, and are notintended to limit embodiments of the invention.

In one example, suppose that EMI emissions are to be maintained belowsome predefined, fixed level in a particular region of anelectromagnetic spectrum if that region is occupied by other users, butin unoccupied regions, the EMI does not need to be confined to anyparticular level, and/or may be higher. Also suppose that devices at agiven location may be allocated regions in the radio frequency spectrumidentified by the frequency range 139.0 to 143.0 MHz, and that EMIemissions are to be maintained below some predefined, fixed level inthose regions. For the given location, suppose that the regionsidentified by the frequency range 140.1 to 142.2 are unoccupied.

In one embodiment, if a given device emits EMI in the region 139.5 to139.7, and if the regions identified by the frequency range 139.5 to139.7 are occupied by other users, then the EMI may be reduced in theregions 139.5 to 139.7, and increased in the regions 140.1 to 142.2,which are unoccupied. In another embodiment, if the emitted EMI levelsare unacceptable in the regions 139.5 go 139.7, then the EMI may bereduced in the regions 139.5 to 139.7, and increased in the regions140.1 to 142.2, where they may be acceptable. In yet another embodiment,if the EMI 106 levels are unacceptable, and the regions 139.5 to 139.7are occupied by other users, then the EMI 106 may be reduced in theregions 139.5 to 139.7, and increased in the regions 140.1 to 142.2.

CONCLUSION

Therefore, in one embodiment, a method comprises determining if a deviceemits electromagnetic interference (EMI) in one or more regions of anelectromagnetic spectrum occupied by other users, and if the deviceemits EMI in one or more regions of an electromagnetic spectrum occupiedby the other users, then reducing the EMI in the one or more regionsoccupied by the other users, and increasing the EMI in one or more otherregions unoccupied by the other users.

The embodiments described herein may reduce EMI in regions occupied byother users. For example, non-communications devices may not be capableof meeting FCC defined EMI levels for all frequencies. By altering theEMI that is emitted into an occupied region of an electromagneticspectrum, the EMI may be reduced from the occupied regions. Incommunications devices, for example, altering the EMI in a way to reduceit from one or more occupied regions of an electromagnetic spectrum, andto increase it in unoccupied regions of the electromagnetic spectrum,may enable the communication devices to increase the power of the signalinjected into the channel. By the Shannon equation, this may alsoincrease the device's transmission capabilities.

Furthermore, embodiments described herein may reduce EMI in areasoccupied by other users without the need to incur shielding costs, oradditional shielding costs, and may furthermore help reduce theshielding costs of a system in which a device is incorporated. Forexample, non-communications devices may use reduced-cost electromagneticshielding, and communications devices may use minimally shielded orunshielded transmission media (such as copper). In these devices,embodiments of the invention may help further reduce EMI withoutincreasing shielding costs.

In the foregoing specification, specific embodiments have beendescribed. It will, however, be evident that various modifications andchanges may be made to these embodiments without departing therefrom.The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

1. A method comprising: determining if a device emits electromagneticinterference (EMI) in one or more regions of an electromagnetic spectrumoccupied by other users; and if it is determined that the device emitsEMI in one or more regions of the electromagnetic spectrum occupied byother users: reducing the EMI in the one or more regions; and increasingthe EMI in one or more other regions of the electromagnetic spectrumthat are unoccupied by the other users.
 2. The method of claim 1,wherein said reducing the EMI in the one or more regions comprisesremoving the EMI from the one or more regions.
 3. The method of claim 1,wherein said method comprises determining if the device unintentionallyemits EMI in one or more regions of an electromagnetic spectrum occupiedby other users, and comprises reducing the EMI in the one or moreregions, and increasing the EMI in one or more other regions if it isdetermined that the device unintentionally emits EMI in one or moreregions of an electromagnetic spectrum occupied by other users.
 4. Themethod of claim 3, wherein the device unintentionally emits EMI in oneor more regions of a radio frequency spectrum occupied by licensed usersof the radio frequency spectrum, and said increasing the EMI results inincreasing the EMI in one or more other regions of the radio frequencyspectrum that arc unoccupied by the licensed users of the radiofrequency spectrum.
 5. The method of claim 1, wherein said determiningif the device emits EMI in one or more regions of the electromagneticspectrum occupied by other users comprises: determining a presence ofother users at the device's location; and determining the one or moreregions of the electromagnetic spectrum occupied by the other users atthe location.
 6. The method of claim 5, wherein said determining thepresence of other users at the device's location comprises: determininga location of the device; and accessing a database of users at thelocation.
 7. The method of claim 5, wherein said determining thepresence of other users at the device's location comprises listening forthe presence of other users.
 8. The method of claim 5, wherein saiddetermining the presence of other users at the location comprisesdetermining the presence of other users licensed at the location.
 9. Anapparatus comprising: circuitry capable of determining if a device emitselectromagnetic interference (EMI) in one or more regions of anelectromagnetic spectrum occupied by other users; and if it isdetermined that the device emits EMI in the one or more regions of anelectromagnetic spectrum occupied by other users, the circuitryadditionally capable of: reducing the EMI in the one or more regions;and increasing the EMI in one or more other regions of theelectromagnetic spectrum unoccupied by the other users.
 10. Theapparatus of claim 9, wherein said circuitry is additionally capable ofremoving the EMI from the one or more regions.
 11. The apparatus ofclaim 9, wherein said circuitry is additionally capable of determiningif the device unintentionally emits EMI in one or more regions of anelectromagnetic spectrum occupied by other users, and of reducing theEMI in the one or more regions, and increasing the EMI in one or moreother regions if the circuitry determines that the deviceunintentionally emits EMI in one or more regions of an electromagneticspectrum occupied by other users.
 12. The apparatus of claim 11, whereinthe device unintentionally emits EMI in one or more regions of a radiofrequency spectrum occupied by licensed users of the radio frequencyspectrum, and said circuitry is additionally capable of increasing theEMI in one or more other regions of the radio frequency spectrumunoccupied by the licensed users of the radio frequency spectrum. 13.The apparatus of claim 9, wherein said circuitry is additionally capableof: determining a presence of other users at the device's location; anddetermining the one or more regions of the electromagnetic spectrumoccupied by the other users at the location.
 14. The apparatus of claim13, wherein said circuitry is additionally capable of: determining alocation of the device; and accessing a database of users at thelocation.